René Bañares-Alcántara

Design support systems for process engineering—II. KBDS: An experimental prototype

Abstract KBDS is a prototype design support system for process engineering. It was created as an experimental vehicle to test and develop ideas about the representation of the design process, and to demonstrate how such a representation can be used to support the design activity. Our starting point is a representation of the design process consisting of three spaces: One for design alternatives, another tor design objectives, and a third for models of the design alternatives. These have been implemented ni a prototype system, and their structure, behaviour, and interaction are described. The implementation is based on two powerful techniques: Object-oriented programming, and assumption-based truth maintenance systems (ATMS). The functionality of KBDS is shown through a demonstration based on the sequential development of a separation system and the hierarchical conceptual design of the HD A process. This demonstration shows that the current capabilities of KBDS satisfy many of the require ments of a design support system, and provide a basis for future expansion to satisfy the others

Decade—A hybrid expert system for catalyst selection—I. Expert system consideration

Abstract DECADE (Design Expert for CAtalyst DEvelopment) is a prototype expert system for catalyst selection. The objective of DECADEs development has been to investigate and evaluate the potential of expert systems technology applied to the solution of chemical engineering problems. DECADEs patricular application problem consists of prescribing a set of catalytic materials that have an acceptable probability of being appropriate for a target reactions. The class of reaction. The class of reactions for which DECADE has specific knowledge is carbon monoxide hydrogenation. Given DECADEs architecture and implementation, it can illustrate the integration of different paradigms along some of the several dimensions of expert systems applications: knowledge representation, problem-solving methods, and levels of knowledge abstraction. All these properties are achieved through the use of different languages (FranzLisp, OPS5, SRL 1.5) brought together in a blackboard model architecture.

Design support systems for process engineering-III. Design rationale as a requirement for effective support

An explicit record of design rationale is an important requirement for effective design support. Such a record may be defined as the information supporting or explaining the decisions made by a designer when generating an artifact. Design rationale can be used to (a) improve the documentation of the design process, (b) verify the design methodology and the resulting design artifact, (c) provide support for the analysis and explanation of the design process, and (d) enhance the re-usability of parts of the design artifact. This paper describes an extension to KBDS, a prototype design support system for conceptual design of chemical processes. The extension makes use of an IBIS representation to record the design rationale and integrates it with the design history maintained by KBDS. Thus, KBDS-IBIS records in an integrated and prescriptive form the specification of the design artifact, the history of its evolution during the design process, and the designers rationale.

Optimisation of process plant layout using genetic algorithms

Abstract The layout of chemical facilities is an activity that is largely carried out by the human designer. Few methods exist for optimising layout. Difficulties in formulating the problem as a mathematical program stem from non- convexities as well as from non-differentiable cost functions. Recent attempts (Penteado and Ciric, 1996) have succeeded in only implicitly including land costs, resulting in layouts which can be excessively conservative from the point of view of safety. The use of stochastic optimisation techniques, though not guaranteed to find the global optimum, has proved to be effective in obtaining good, practical solutions and permits the incorporation of more realistic cost functions and constraints. In this research, experiments were carried out using various genetic algorithm formulations, and the resulting program, which includes a useful graphical interactive component, is presented here.

The scope of application of multi-agent systems in the process industry: three case studies

Abstract It has been suggested that multi-agent systems (MAS) are specially adequate for the solution of problems with a dynamic, uncertain and distributed nature. Within industrial applications, there is a wide spectrum of problems with these characteristics, in particular those covering the modelling of artifacts, methodologies and organisations. Three case studies on the application of MAS in the process industry are presented. All of them relate to tools that are being developed to support very diverse core tasks in the process industry (and, by extension, the petroleum industry): • An intelligent search system composed of Internet information agents which are able to gather, compile and classify data available in web pages related to a specific technological domain. This search engine is the first step towards the construction of a knowledge management platform that will allow chemical process industries to improve their capabilities to monitor, predict and respond to technological trends and challenges. • A system to support the concurrent design of processes, to ease communication between engineers who perform design and keep them informed about the progress of the design process. • A tool to support the configuration of work teams. This tool will assist in the configuration of the most suitable team for a specific project. It takes into account the ideal size of the team (2 to n members); its specific composition (managers, engineers/scientists, assistants, etc.); and the proposed type of organisation (centralised, tree hierarchy, etc.). These case studies are representative of a large variety of the possible applications of agent based systems in the process industry.

Development of an expert system for physical property predictions

Abstract In this article we describe the steps followed to develop a prototype expert system called CONPHYDE (CONsultant for PHYsical property DEcisions). Using the framework of the existing expert system PROSPECTOR, CONPHYDE is designed to aid an engineer in the selection of an appropriate vapor-liquid equilibrium method when performing various process calculations. We also present the structure of the inference networks in CONPHYDE which capture the intent of the 37 heuristic rules that from the knowledge base on which the current version is based. An example session with CONPHYDE demonstrates its ability to ask questions in an “intelligent” sequence and provide “expert” advice based on them. The session also illustrates CONPHYDEs (i.e. PROSPECTORs) ability to explain on request why it is asking certain questions and why it is offering the advice it is.

Design support systems for process engineering. I: Requirements and proposed solutions for a design process representation

Abstract Design is an important engineering activity, arguably the most important, because it is the basis for developing new products. An effective design support system can enhance the design process, and thus improve the design product. A number of requirements make the development of a design support system a complex task; useful and directed assistance requires a representation of the design process to be kept in a computable form. The system should furthermore have the flexibility to provide support for exploration, evolution, cooperation, and integration. The described work addresses the above issues, and proposes solutions for their achievement using the exploration-based model of design of Smithers et ai and the hierarchical decision procedure of Douglas. It proposes a fundamentally new representation consisting of three interconnected networks for the design objectives, alternatives, and models respectively, and examines the behaviour or functionality they must provide. Expected benefits from this representation are maintenance of consistency during the design process; dependency-directed redesign or retrofit; reuse of parts of the artifact or the design methodology; enhanced documentation and explanation of the systems actions or advice; representation of multiple points of view and their interactions; and eased verification, modification and maintenance of the design product.

DECADE—a hybrid expert system for catalyst selection—II. Final architecture and results

Abstract DECADE is a prototype knowledge-based system for catalyst selection. From a specified reaction it attempts to propose a set of materials with high probability of being good catalysts for the input reaction and the conditions at which the proposed catalysts should operate. While the first paper on DECADE (Banares-Alcantara et al. , (1987) concentrated on the organization and control aspects of DECADE from the expert systems point of view, this paper presents in more detail the organization of the program and, in particular, the selection strategy from the chemistry point of view. Specifically, there are three levels of responding to a request for catalyst selection: 1. 1. Responding with catalysts that are known to work from published experimental results and that are in the DECADE knowledge base. 2. 2. Classifying the reaction from generic to specific classes and recommending catalysts known to catalyze reactions in all of these levels of classification. 3. 3. Determining both required and unwanted surface steps (adsorption, desorption, dissociation, addition) for the reaction, and selecting materials known to catalyze the required steps and to suppress the unwanted ones. The most interesting results are produced at the deeper level of abstraction (which relies only on medium to deep level knowledge). Catalysts are proposed at this level using a generate and test procedure with a priori and dynamically-generated constraints. Explanation of the results is available for any material that was taken into consideration (whether recommended or not). In view of the limited size of the knowledge base, the results and explanations for this level of abstraction are satisfactory. The operation of DECADE is achieved through the interaction of several modules written in different languages and communicated by means of a blackboard system. The size of DECADE is roughly 300 production rules (in OPS5, Forgy, 1981), 325 frames (in SRL, Wright and Fox, 1983) and 200 functions (in FranzLisp, Foderaro, 1981).

Minimising environmental impact using CBR: An azeotropic distillation case study

Abstract This paper describes a Case Based Reasoning (CBR) system which aids the design of process sequences aimed at the separation of ternary mixtures containing azeotropes. The solution of such tasks is a non-trivial process particularly since many factors including environmental impact must be considered. CBR is an appropriate technique for design since it is rare that a completely new problem is encountered and thus solutions for previous problems found to be environmentally acceptable may be adapted to suit the current situation. The system is able to store, categorise and retrieve appropriate design cases for this class of problem. Also, the system stores indexed design cases within a library. These are organised according to an existing classification system for azeotropic mixtures which enables appropriate cases to be retrieved rapidly and efficiently. Additionally, it is possible for the system to produce an abstract description of the RCM and separation process, so that the designer may more easily apply the library case to the problem in hand. This description is also the first step towards the automation of the case adaptation step. Finally, a case study is presented which illustrates the use of the system.

Conceptual design of wastewater treatment plants using a design support system

A case study showed the advantages of using a design support system during the design and retrofit of wastewater treatment plants (WWTP). The Manresa WWTP was chosen to demonstrate these advantages. While the records of the decision-making process used during the Manresa WWTP design were not available to the authors, its original design objectives and the resulting structure and values for its more important variables were. A simplified but plausible design history focusing on the design decisions and not on the detailed modelling of the WWTP was generated with this information. Using such a design history it is possible (1) to evaluate automatically the compliance of alternative design proposals with respect to the design objectives; (2) to study the influence of the weight of the arguments in the selection of the most adequate proposal; (3) to document the decision-making process; and (4) to assist the designer in the search of specific items within the historical records during the review of the current design or during the retrofit of the plant. © 2000 Society of Chemical Industry